Table cache_extensions is handled by ext:extensionmanager and should be
moved to its namespace. It is now in line with the according extbase
model and called tx_extensionmanager_domain_model_extension.

Change-Id: I9d8e0981bf5ff35c38c3254672b8b8015c72ff47
Resolves: #39922
Related: #39726
Releases: 6.0
Reviewed-on: http://review.typo3.org/13884
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters
Reviewed-by: Philipp Gampe
Tested-by: Philipp Gampe
Reviewed-by: Helmut Hummel
Tested-by: Helmut Hummel